Not engine braking or not coasting
If you drive a manual transmission vehicle, it's good practice to use downshifting, or engine braking, to help slow the car. The engine’s compression will help reduce the load on the brake system increasing brake life while having no ill effects on the engine. Or if you drive a car with an automatic transmission, you should try to get in the habit of coasting to maintain speed. Many drivers are either pressing the gas or pressing the brake at all times. But really you can take your foot off both pedals and let the vehicle coast and use its rolling and wind resistance to maintain your speed. This will not involve any brake use, thereby increasing brake life.
Riding the brake pedal/driving two footed
One of the first things we are all taught when learning to drive a car with an automatic transmission is to only use one foot. However some people can't help themselves. With that said, many two-footed drivers tend to leave a foot on the brake pedal at all times. Even the slightest pressure on the brake pedal can end up pressing the pads against the rotors and reducing the life of your brake system. Another way this can happen is if during coasting you rest your foot against the brake pedal. When you aren’t using either pedal, make sure your feet aren't inadvertently pressing against the brake pedal. Driving like this will reduce brake life, but also reduce MPGs since the engine has to fight against the brake system.
Driving too close to the car in front of you/tailgating
Tailgating is a bad plan no matter how you look at it. Reducing your reaction time by driving so close to the car in front of you is dangerous. But it can also be dangerous for your brakes. When you tailgate, the tendency is to make more speed corrections to maintain the close proximity to the car in front of you. Constantly bouncing between accelerating, and braking will contribute to reduced life from your pads and rotors as well as affect your gas mileage. (See engine braking & coasting above)
Not driving the car often enough
This one may seem counterintuitive, but it makes sense when you think about it. When a car sits without being driven, hoses can rot, gas can go bad, and rotors can get some surface rust, or even transfer pad material to the rotor if put away hot. The basic rule of thumb with any car is to at least drive them occasionally. This makes sure that the fluids circulate, that gas in the lines gets freshened up with more from the tank, and the minor surface rust on your rotors gets wiped off by the brake pads. This is important, because rust wants to damage your entire iron rotor, as it continues to expand and corrode the iron as long as you allow it to. So it's very important that you drive your car occasionally to allow the pads and rotors to remove the surface rust to avoid more significant damage.
Braking through turns
This one may be a bit less obvious than some of the others, but as you may have noticed, many of the ways you can increase the life of your brakes is related to using them less often. Now, clearly, we aren't suggesting you don't use your brakes, we are just demonstrating ways that people use them when it isn't necessary. For example, when turning. When you come to a turn, ideally you want to let off the brake and actually mildly accelerate through the turn. When you do this, the chassis can load down on the suspension which adds more traction, and it allows the vehicle’s differentials to apply the correct power to the correct wheels and actually help pull the car through the turn. This makes for a more comfortable ride, while also reducing the amount of brake use, which we all know will help extend the life of your brake system.